1. Field of the Invention
The invention relates to the field of video displays particularly raster scanned, cathode ray tube displays.
2. Prior Art
In recent years, computer-aided designs (CAD) have become widely used in many fields. Architects, engineers, scientists and others rely on computers, not only for routine computations but for more sophisticated purposes such as for prediction and simulation.
Often a visual display cathode ray tube (CRT) forms an integral part of a CAD system since visual depictions are indispensable for most designing. Complex structures can be moved, rotated, expanded and color coded on some displays providing perceptions otherwise unobtainable. In some fields, it is impossible to produce competitive products without a CAD. This is particularly true in the semiconductor industry.
A considerable amount of computer time is required to provide the displays in computer-aided design systems. By way of example, what appears to be the simple rotation of a symbol on a screen requires the movement of substantial amounts of data in memory. Other visual display effects such as highlighting of symbols, etc., while simply perceived, require substantial manipulations and consequently burden the computer.
As will be seen, the present invention provides a display system which readily facilitates the display of symbols and their rotation in addition to other display techniques.